When filtering hot gases at high temperatures, for example when cleaning flue gases in combustion plants, filter elements of a ceramic type of many different embodiments are used today. In one embodiment filters may be composed of a large number of filter elements in a large filter container. This container is provided at its upper part with an outlet for cleaned gases and at its lower part with a collection space for dust separated in the filter and fallen down from the filter elements. Uncleaned gas enters the space below the filter elements at the side of the container. The filter elements may be suspended from a plate, provided with holes, in the upper part of the container where the plate supports the individual filter elements. Each hole in the plate is equipped with a filter element suspended below the hole, which filter element cleans the gases which flow through the filter element and further out through that hole in the plate which is associated with the respective filter element, the gas above the plate thus becoming free from dust and being brought to the outlet of the filter container. Dust from the uncleaned gas will adhere to the outside of the different filter elements. This dust will loosen when a gas is brought to pass through the filter elements in reverse direction during periodically recurring cleanings of the filter compound. The dust from the collection space is fed out at the lower part of the container.
Ceramic materials included in filters of the kind described above have a stochastic composition from the point of view of strength, which is caused by the fact that in each produced ceramic component imperfections exist in the internal structure of the ceramic. This may lead to breakage of the component if it is subjected to stress, for example in the form of temperature transients.
In a filter with many filter elements there is always a risk that one or more filter elements will break, usually in such a way that part of the filter element walls down from its position. The consequence of this breakage of the filter element is that a certain part of the gas, that part which passes through the broken filter element, is admitted through this element in uncleaned state, which is totally unacceptable since a sub-quantity of completely uncleaned gas will flow out of the filter elements.
The filter elements in the above-described type of filters are suspension-mounted and are relatively heavy. When such a filter element is broken, a breakage of the whole filter element occurs, whereby the lower part or parts of the broken filter element fall(s) down.